Radiotherapy is used for treating cancer or reducing a patient's pain by killing or no longer proliferating cancer cell so that the cancer cells die due to the end of the lifetime.
Such radiotherapy is performed, for example, for preventing recurrence when there is a large possibility that the cancer cells remain after surgery, a case where the surgery cannot be performed, a case where radiotherapy is more effective than the surgery, a case of enhancing the quality of the patient's life in combination of surgery and radiotherapy, or minimizing an anti-cancer effect in combination of anti-cancer chemotherapy.
The radiotherapy is performed by a medical device including a radiation generator such as a linear accelerator. The linear accelerators has been used as a current standard device for radiotherapy by outputting high energy X-rays or electron beams and finely adjusting an output radiation dose.
It is necessary to control appropriately a radiation dose output from a radiotherapy device when the radiotherapy is performed. The best treatment effect may be obtained by irradiating an optimal dose of radiation corresponding to a condition, size or depth of the tumor and an effect on other organs adjacent to an organ with the tumor (for example, a phenomenon in which the rectum adjacent to the prostate is damaged by radiation during treatment of prostate cancer), and thus, it is very important to form an optimal dose distribution by irradiating radiation of the linear accelerator.
As a result, before using a radiotherapy device, it is necessary to confirm in advance operational precision such as whether the accelerator operates properly, especially whether a planned radiation dose is transmitted by normally controlling the radiation dose. In addition, it is preferred that the operation of the linear accelerator and the radiation does measure an absorbed dose delivered to a specific part in the body of the patient to be actually treated. The thing used for this purpose is called a phantom in the medical field and a measurement device made to measure the radiation instead of the body.
On the other hand, it is preferable to minimize a radiation exposure dose to the rectum while simultaneously delivering a maximum radiation dose to the tumor, in order to prevent the rectum as a main protective organ from being damaged by the radiation during treatment of prostate cancer. Therefore, for effective treatment, it is necessary to predict a dose value delivered to the patient before radiotherapy, particularly, a dose distribution delivered to the tumor and the rectum. As a result, there is a need for a rectal phantom capable of verifying the accuracy of the dose distribution delivered to the rectum during radiotherapy of the prostate by simulating the rectum of the patient.